1. Field of the Invention
The invention relates to an installation member for service ducts whose rear walls are provided with longitudinal grooves having an essentially T-shaped cross-section. The installation member comprises an approximately rectangular bottom part with a central longitudinal slot into which an approximately Z-shaped clamping lever is placed in such a way that, in the assembled state, the arm of the lever on the top side of the bottom part is placed flat on this top side and the arm of the clamping lever on the bottom side of the bottom part engages in the groove and presses the installation member against the walls of the groove.
A large number of service ducts are known, for example, from German Offenlegungsschrift No. 21 23 958, German Auslegeschrift No. 12 16 957, German Auslegeschrift No. 12 76 153, German Auslegeschrift No. 20 17 232 or German Utility Model 77 11 728. These ducts are usually made of extruded, thermoplastic material, of extruded aluminum or profiled sheet steel. The open side of the duct may be covered with a cover. The ducts are mounted on ceilings, walls, under window railings, on laboratory tables etc.
2. Description of the Prior Art
Special installation members are required for fastening electrical installation devices, for example, sockets, switches, remote control receivers etc., in such ducts. Such installation members are described, for example, in German Utility Model Nos. 70 47 743 and 77 28 102. These installation members are boxes into which commercially available devices can be inserted. The box serving as installation member is fastened to the rear wall of the duct by means of a Z-shaped clamping element. This clamping element is inserted through a central slot in the bottom of the installation member in such a way that it engages the longitudinal groove of the duct and, in the assembled position when the inner arm of the clamping element rests against the bottom, effects a clamping connection between the wall of the longitudinal groove and the bottom part of the installation member.
In the structures described above, the Z-shaped bent clamping element is still relatively large. Assembly and disassembly are only possible if the box is empty. However, this simple structure is particularly in need of improvement because of the fact that the clamping element effects a connection only with one of the walls of the groove.
A structure in which the forces are transmitted over a large area and uniformly from the installation member to the walls of the groove is known from German Offenlegungsschrift No. 33 05 602. This structure is particularly adapted for the installation of electrical installation equipment which causes high mechanical forces to be generated during use, for example, high-voltage circuits, etc. However, in order to reach the desired goal, a substantial mechanical and structural expenditure is required.
It has been found that such a great expenditure is not always necessary while, on the other hand, the simple clamping device of the boxes described above is not sufficient, or results in certain electrical problems. Therefore, it is the object of the present invention to provide an installation member of the aforementioned type in which a distribution of the clamping forces is possible to both groove walls and which is of simple construction.